AMYQ: An index to standardize quantitative amyloid load across PET tracers

Introduction Positron emission tomography (PET) amyloid quantification methods require magnetic resonance imaging (MRI) for spatial registration and a priori reference region to scale the images. Furthermore, different tracers have distinct thresholds for positivity. We propose the AMYQ index, a new...

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Published in	Alzheimer's & dementia Vol. 17; no. 9; pp. 1499 - 1508
Main Authors	Pegueroles, Jordi, Montal, Victor, Bejanin, Alexandre, Vilaplana, Eduard, Aranha, Mateus, Santos‐Santos, Miguel Angel, Alcolea, Daniel, Carrió, Ignasi, Camacho, Valle, Blesa, Rafael, Lleó, Alberto, Fortea, Juan
Format	Journal Article
Language	English
Published	United States John Wiley and Sons Inc 01.09.2021
Subjects	Aged Alzheimer Disease - metabolism Alzheimer's disease Amyloid - metabolism amyloid burden standardization amyloid pet amyloid pet quantification Australia centiloid Female Humans Magnetic Resonance Imaging Male Neuropathology Positron-Emission Tomography - standards United States Australia United States centiloid amyloid burden standardization amyloid pet amyloid pet quantification Alzheimer's disease neuropathology
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ISSN	1552-5260 1552-5279 1552-5279
DOI	10.1002/alz.12317

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Summary:	Introduction Positron emission tomography (PET) amyloid quantification methods require magnetic resonance imaging (MRI) for spatial registration and a priori reference region to scale the images. Furthermore, different tracers have distinct thresholds for positivity. We propose the AMYQ index, a new measure of amyloid burden, to overcome these limitations. Methods We selected 18F‐amyloid scans from ADNI and Australian Imaging, Biomarker & Lifestyle Flagship Study of Ageing (AIBL) with the corresponding T1‐MRI. A subset also had neuropathological data. PET images were normalized, and the AMYQ was calculated based on an adaptive template. We compared AMYQ with the Centiloid scale on clinical and neuropathological diagnostic performance. Results AMYQ was related with amyloid neuropathological burden and had excellent diagnostic performance to discriminate controls from patients with Alzheimer's disease (AD) (area under the curve [AUC] = 0.86). AMYQ had a high agreement with the Centiloid scale (intraclass correlation coefficient [ICC] = 0.88) and AUC between 0.94 and 0.99 to discriminate PET positivity when using different Centiloid cutoffs. Discussion AMYQ is a new MRI‐independent index for standardizing and quantifying amyloid load across tracers.
Bibliography:	http://adni.loni.usc.edu/wp,content/uploads/how_to_apply/ADNI_Acknowledgement_List.pdf Data used in preparation of this article were obtained from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database (adni.loni.usc.edu). As such, the investigators within the ADNI contributed to the design and implementation of ADNI and/or provided data but did not participate in the analysis or writing of this report. A complete listing of ADNI investigators can be found at https://aibl.csiro.au/about/aibl‐research‐team ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 Data used in preparation of this article were obtained from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database (adni.loni.usc.edu). As such, the investigators within the ADNI contributed to the design and implementation of ADNI and/or provided data but did not participate in the analysis or writing of this report. A complete listing of ADNI investigators can be found at: http://adni.loni.usc.edu/wp,content/uploads/how_to_apply/ADNI_Acknowledgement_List.pdf
ISSN:	1552-5260 1552-5279 1552-5279
DOI:	10.1002/alz.12317